The present invention relates generally to an imaging apparatus and fuser components thereof for use in electrostatographic, including digital, apparatuses. The fuser components, including fuser members, pressure member, donor members, external heat member, and the like, are useful for many purposes including fixing a toner image to a copy substrate. More specifically, the present invention relates to fuser components comprising a polyimide outer layer. In embodiments, the polyimide outer layer is positioned on a substrate, which may be of many configurations including a roller, belt, film, or like substrate. In other embodiments, the polyimide outer layer has an outer release layer thereon. In embodiments, there is positioned between the substrate and the outer polyimide layer, an intermediate and/or adhesive layer. In embodiments, the fuser member is a pressure member, such as a pressure belt. The present invention may be useful as fuser members in xerographic machines, including color machines.
In a typical electrostatographic reproducing apparatus, a light image of an original to be copied is recorded in the form of an electrostatic latent image upon a photosensitive member and the latent image is subsequently rendered visible by the application of electroscopic thermoplastic resin particles which are commonly referred to as toner. The visible toner image is then in a loose powdered form and can be easily disturbed or destroyed. The toner image is usually fixed or fused upon a support, which may be the photosensitive member itself, or other support sheet such as plain paper.
The use of thermal energy for fixing toner images onto a support member is well known and methods include providing the application of heat and pressure substantially concurrently by various means, a roll pair maintained in pressure contact, a belt member in pressure contact with a roll, a belt member in pressure contact with a heater, and the like. Heat may be applied by heating one or both of the rolls, plate members, or belt members. With a fixing apparatus using a thin film in pressure contact with a heater, the electric power consumption is small, and the warming-up period is significantly reduced or eliminated.
It is important in the fusing process that minimal or no offset of the toner particles from the support to the fuser member take place during normal operations. Toner particles offset onto the fuser member may subsequently transfer to other parts of the machine or onto the support in subsequent copying cycles, thus increasing the background or interfering with the material being copied there. The referred to xe2x80x9chot offsetxe2x80x9d occurs when the temperature of the toner is increased to a point where the toner particles liquefy and a splitting of the molten toner takes place during the fusing operation with a portion remaining on the fuser member. The hot offset temperature or degradation of the hot offset temperature is a measure of the release property of the fuser, and accordingly it is desired to provide a fusing surface, which has a low surface energy to provide the necessary release. To ensure and maintain good release properties of the fuser, it has become customary to apply release agents to the fuser roll during the fusing operation. Typically, these materials are applied as thin films of, for example, silicone oils to prevent toner offset.
Another important method for reducing offset, is to impart antistatic and/or field assisted toner transfer properties to the fuser. However, to control the electrical conductivity of the release layer, the conformability and low surface energy properties of the release layer are often affected.
U.S. Pat. No. 5,411,779 to Nakajima et al. discloses a composite tubular article for a fusing belt comprising a tubular inner layer of polyimide and fluoroplastic outer layers.
U.S. Pat. No. 5,309,210 to Yamamoto discloses a belt apparatus comprising a base layer polyimide and a fluorine resin outer layer.
U.S. Pat. No. 5,149,941 to Hirabayashi and U.S. Pat. No. 5,196,675 to Suzuki, both disclose an image fixing apparatus comprising an electrically insulating material base layer and low resistance surface layer insulating member comprised of a polyimide.
U.S. Pat. No. 5,532,056 teaches a fixing belt comprised of a polyimide resin.
U.S. Pat. No. 6,066,400 discloses biasable components comprising polyimides.
U.S. Pat. No. 5,761,595 discloses intermediate transfer components having a polyimide substrate and a fluorinated carbon filled fluoropolymer layer.
U.S. Pat. No. 6,201,945 discloses polyimide fuser components having doped metal oxides dispersed therein.
Known fuser coatings include high temperature polymers such as polytetrafluoroethylene, perfluoroalkoxy, fluorinated ethylene propylene, silicone rubber, fluorosilicone rubber, fluoroelastomers, and the like. These coatings have been found to have adequate release properties and control toner offset sufficiently. However, these coatings do not tend to stay clean during use. Further, the coatings do not maintain a uniform surface. More specifically, the coatings often wear during use and/or become scratched during operation. In addition, these known surfaces often react with the toner and/or oil and/or debris from media, which causes the surface to become dirty and/or contaminated. The surface can, in turn, become physically damaged. The result of these problems is that the fuser member has a reduced useful function and short life. Another problem resulting from release coatings with high friction is unacceptable copy or print quality defects. The high friction often associated with conformable coatings may result in the generation of waves in the media being fused and/or the fuser member itself. This, in turn, results in copies or prints with localized areas of poorer fix and/or differential gloss.
Therefore, a need remains for fuser components for use in electrostatographic machines that have superior mechanical properties, including a the ability to remain clean and uniform during use. A further need remains for fuser coatings having reduced susceptibility to contamination, scratching, and other damage. In addition, a need remains for a fuser component having a longer life. In addition, a need remains for a fuser component with low friction while being resistant to scratching and other damage.
The present invention provides, in embodiments, a fuser component comprising a substrate, and thereover, an outer layer comprising a polyimide.
The present invention further includes, in embodiments, a pressure belt comprising a polyimide substrate, and thereover, an outer layer comprising a polyimide.
Moreover, the present invention provides, in embodiments, a fuser member comprising a substrate and thereover, an outer layer comprising a polyimide and filler, wherein the filler is selected from the group consisting of polytetrafluoroethylene powder, copper oxide, and mixtures thereof.
In addition, the present invention provides, in embodiments, an image forming apparatus for forming images on a recording medium comprising a charge-retentive surface to receive an electrostatic latent image thereon; a development component to apply toner to the charge-retentive surface to develop an electrostatic latent image to form a developed image on the charge retentive surface; a transfer film component to transfer the developed image from the charge retentive surface to a copy substrate; and a fusing component for fusing toner images to a surface of the copy substrate, the fusing component comprising a substrate, and thereover an outer layer comprising a polyimide.